1. Field of the Invention
This invention relates generally to rotary kilns and more specifically to improvements in such rotary kilns that aid in the removal of large lumps of material or the like from the interior of the kilns.
2. Description of the Prior Art
Rotary kilns are used for various purposes. For example, such rotary kilns are used in the paper mill industry for "burning lime", i.e., for heating calcium carbonate (limestone) to cause the calcium carbonate to decompose into calcium oxide (quicklime) and carbon dioxide. In such an operation, wet lime mud is introduced in the upper end of the rotary kiln and the lower end of the rotary kiln is fired with natural gas or oil. The burned quicklime exits from the lower end of the kiln in the form of particles ranging preferably from dust to 1 in. in diameter. Frequently, however, the lime mud congeals into larger particles which may range from three to four inches to two feet in diameter and these also tumble from the lower end of the kiln. Ordinarily, the lime particles pass through a grill or grate and are conveyed to a storage bin or the like. However, the large particles which cannot pass through the grill are retained on the grill at the lower end of the kiln and have to be removed manually by the operator of the kiln and transferred to a crusher or the like. The manual task of dragging these large lumps of lime from the hot fiery end of the kiln is a very taxing, unpleasant, and somewhat dangerous task.
Applicant is aware of the following U.S. patents which may be of interest: Tomlinson, U.S. Pat. No. 1,544,504; Phillips, U.S. Pat. No. 2,518,636; Harris, U.S. Pat. No. 3,124,338; Spence, U.S. Pat. No. 3,220,714; Smithwick, U.S. Pat. No. 3,604,692; Vering, U.S. Pat. No. 3,807,936; and Henning, U.S. Pat. No. 3,910,756. None of these patents disclose, teach or suggest the present invention.